This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The ultimate inability of the immune system to eliminate cytomegalovirus (CMV) from the host is likely due to sophisticated viral evasion mechanisms that target many aspects of the host immune system. In this project, we will try to gain a better understanding of the molecular mechanisms by which CMV modulates the induction of innate immune responses, particularly the interferon response. Specific Aim 1 is to identify how HCMV activates interferon-regulatory factor 3 (IRF3). This aim has been completed and the results have been published. Specific Aims 2 and 3 are to determine how human and rhesus CMV interfere with IRF3-dependent transcriptional induction of interferon-stimulated genes (ISGs). We have tested our original hypothesis that the tegument proteins pp65 and pp71 are responsible for inhibiting IRF3 activation by RhCMV by generating deletion viruses. However, since these viruses still inhibit IRF3 activation, we now hypothesize that RhCMV contains additional IRF3 inhibitory genes. Current experiments are aimed at identifying these genes. In addition, we now explore the inhibition of IFN-dependent ISG induction by RhCMV and we have generated evidence that HCMV also inhibits IRF3 activation.